David Hatt's eardrums had long absorbed the din from aircraft, hunting rifles and heavy machinery.
The barrage hit an apex last summer when he lit an acetylene torch and accidentally sparked a fiery explosion.
"It actually blew me backward about 10 feet," recalled the Downingtown man.
His hearing returned a few hours later. But the tinnitus that had long plagued Hatt intensified.
"It sounds like someone blowing a whistle in your ear 24 hours a day," said Hatt, 61, who started to lose sleep, and became fatigued and depressed.
The prognosis wasn't good.
Medicine has been stumped by the mysterious tones that afflict an estimated 50 million people in this country and severely disrupt the lives of about 2 million.
Sufferers are often advised to learn to live with the noise.
But then Hatt found A&E Audiology Inc. in Lititz.
Dr. Kamal A. Elliot, the clinic director, had recently introduced a new therapy based on a digital music player manufactured by Neuromonics Inc., an Australian company whose headquarters are now in Bethlehem.
Patients desensitize their brains to tinnitus by listening to the lightweight MP3-like player at least two or three hours a day over six months.
Hatt, who began plugging in about two months ago, reported "a new lease on life."
Independent studies have yet to quantify the effectiveness of the treatment, which is expensive (ballpark, $5,000, including unit, therapy and doctor's office visits), and often not covered by insurance.
Still, Elliot said, Neuromonics promises to turn down the volume on a maddeningly persistent problem.
"You always had a little sense of frustration because you thought, 'Ooh, I wish I could do something for these people.' "
Tinnitus sufferers often have some degree of hearing loss and hyperacusis, or extreme sensitivity to noise.
The condition takes many forms, including beeping, buzzing, clicking, hissing, roaring and ringing.
Its many triggers include excessive noise, head trauma, disease, aging and side effects from medication.
The phantom sounds often match the hearing loss frequency, said Elliot, who rules out medical causes before starting treatment.
Researchers theorize that tinnitus occurs when the brain creates an internal substitute for exterior sounds the ear can no longer detect.
According to Elliot, "The brain kind of turns up the volume" and then perpetuates the sensation by stimulating the limbic structures that govern emotion, behavior and long-term memory.
The disorder can wreak emotional havoc, according to Elliot, who said the tinnitus population has a higher rate of suicide.
"They have a sound in their head and they can't get it out."
But the field is abuzz with new treatments.
Promising options include drugs, biofeedback, noninvasive magnetic therapy and a controversial procedure in which surgeons implant tinnitus-suppressing electrodes in the brain.
Another approach, invented by neuroscientist Pawel J. Jastreboff, involves piping white noise into the ear via hearing-aidlike devices.
The goal of Jastreboff's tinnitus retraining therapy is to break the brain's association between faulty neural signals and unpleasant sensations.
Neuromonics tackles the problem with specially blended music.
In the 1990s, Australian audiologist Dr. Paul Davis had the idea to digitally embed tinnitus-masking sounds into mellow classical and New Age tracks.
The broadband masking sounds span the auditory spectrum and are tailored to each person's hearing ability.
Patients typically use the Federal Drug Administration-cleared device when their tinnitus bothers them most.
"We're getting their limbic system to stop focusing on the sound," said Elliot, who sometimes prescribes the therapy in conjunction with hearing aids.
The Neuromonics player monitors patients' usage, she said. The information can be downloaded and the program tweaked throughout the treatment.
Neuromonics Chief Executive Officer Rick Giancola said the seven-year-old company has provided training for more than 200 clinics and sold thousands of units in the United States.
The Neuromonics market also extends to Australia, Singapore and New Zealand, and is expected to expand to Europe and Asia next year, he said.
"It's really gained traction in the past 12 months," added Giancola, who said last month's sales are five times greater than May 2007 sales.
According to two small, peer reviewed studies funded by Neuromonics, Giancola said, 90 percent of the patients queried reported clinically significant reduction of tinnitus.
"We are constantly improving the algorithms" used to mix the broadband sound with the music, he added.
In an increasingly noisy world, he said, "We feel we will … become the gold standard" for tinnitus treatment.
Elliot said she got excited about Neuromonics when she heard about the concept two years ago.
However, she cautioned, "There is no treatment that is 100 percent. … We definitely need more studies, but it's promising."
Hatt, who has diabetes, heart disease and midrange hearing loss, has become an advocate for ear protectors.
And he swears by his Neuromonics player.
He said he initially listened to it three or four hours a day and saw results after 10 days.
He now tunes in at least two hours a day, he said.
"If I'm eating lunch or something I'll put it on a half-hour at a time."
"Right now, I still hear [tinnitus] a little bit but it doesn't affect my sleep.
"It's very expensive to have the treatment done," he said, but "for me, it's worked very well."
Jon Rutter is a staff writer for the Sunday News. His e-mail address is jrutter@lnpnews.com.
